Fluid retarder



United States Patent Inventor Eugene y 2,416,193 Meyers /54X Royal Oak, 2,630,683 3/1953 Wemp.... 60/54x pp 761,270 2,672,953 3/1954 Cline l88/90A fi t d g n 2 2 3,156,335 1 1/1964 Nlden.... 60/54X aten e BC- 9 3,291,268 12/1966 Na e1 192 4B Assignee Eaton Yale & Towne Inc. g

Cleveland, Ohio Prunary Examiner-Edgar W. Geoghegan a corporation of Ohio Atlorneywoodhams, Blanchard and Flynn FLUID RETARDER 17 Claims Drawing Figs ABSTRACT: A flu d torque transfer device having a pair of bladed members axially spaced from one another to define a [1.5. CI 188/90, pwssure creating Zane and a discharge gap therebetween The 60/54 discharge gap has fluid accumulation means in fluid communi- F16! 57/00 cation therewith so that the fluid discharged through the gap Fleld ofSearch 60/54; n collect i the fluid accumulation means Means are 192MB; 188/901): vided to ensure the occurrence of a low pressure downstream of the discharge gap so that the fluid pressure in the accumula- References cued tion means is always less than the fluid pressure in the pressure UNITED STATES PATENTS creating zone so that a major pressure drop will occur across 2,241,189 5/1941 Dick 60/54UX the discharge gap. 1

3/ 62 X 5/ y 3 69- -ig- 42 52 6 X 7! a, J 47 X/[A 7 QYK/M/l y 41 44 77 T PM 7 2 L FQIEW/E FLUID RETARDER FIELD OF THE INVENTION BACKGROUND OF THE INVENTION Fluid torque transfer devices such as retarders and fluid couplings have been known for many years and have been used in many and varied applications. However, their use in high-speed applications has not been entirely satisfactory due to excessive operating temperatures developed in the fluid, cavitation problems and excessive leakage.

Furthermore, those known fluid torque transfer devices which did not operate at high speeds did not generate enough pressure within the toroid and therefore required a scroll or cover across the fluid discharge gap immediately adjacent the downstream side thereof to restrict the flow of fluid through the discharge gap to permit a buildup in pressure. Check valves were also provided in the scroll to limit the maximum extent of the buildup in pressure within the toroid. However, such known devices have been unsatisfactory for high-speed operation due to their excessively large. size and the high volume of fluid required to generate the degree of coupling desired.

Accordingly, the objects of this invention include:

1. To provide a fluid torque transfer device for use in highspeed applications and which is a small and compact arrangement for installation into vehicles, such as automobiles and trucks, and yet capable of utilizing a high volume of fluid in order to generate the degree of coupling desired;

2. To provide a fluid torque transfer device, as aforesaid, wherein the generation of heat within the fluid is generally not excessive and hence not a problem; I

3. To provide a fluid torque transfer device, as aforesaid, wherein cavitation problems have been minimized;

4. To provide a fluid torque transfer device, as aforesaid, which can be easily installed in existing'highsspeed devices;

5. To provide a fluid torque transfer device, as aforesaid, which is durable and maintenance free; and

6. To provide a fluid torque transfer device, as aforesaid, which is relatively simple to manufacture, and is composed of readily available parts and therefore inexpensive to manufacture.

Other objects and purposes of this invention will be apparent to persons acquainted with fluid torque transfer devices of this general type upon reading the following specification and inspecting the accompanying drawings, in which:

FIG. 1 is a schematic illustration of one type of application for the fluid torque transfer device embodying the invention;

FIG. 2 is a central longitudinal sectional view of the fluid torque transfer device;

FIG. 3 is a central longitudinal sectional view of a modified fluid torque transfer device;

FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3;

FIG. 5 is a central longitudinal sectional view of a modified fluid torque transfer device; and

FIG. 6 is a central longitudinal sectional view illustrating a modification of the embodiment shown in FIG. 5.

Certain terminology has been used h'ereinabove and will be used hereinbelow for convenience in reference only and will not be limiting. The words up, down," right and left will designate directions in the drawings to which reference is made. The words in and out" will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.

The term fluid torque transfer device" is used to denote a device which is comprised of two relatively rotatable It is to be understood that this term is to include those devices wherein one of the members is fixed as well as those devices wherein both of the members are rotatable. Thus, term fluid torque transfer device" is to refer to such devices commonly known as fluid retarders" and fluid couplings.

SUMMARY OF THE INVENTION The objects and purposes of the invention are met by providing a fluid torque transfer device having a pair of axially spaced bladed members defining a pressure creating zone and a discharge gap therebetween, and having means insuring a low pressure against the downstream side of the discharge gap so that a major pressure drop will occur across the discharge DETAILED DESCRIPTION Referring first to FIG. 1, a fluid torque transfer device 10 is connected to the output of a gas turbine engine 11. The engine 11 is of the free turbine type as commonly used in land vehicles, such as automobiles and trucks, and comprises compressor apparatus 12, combustion apparatus 13 and a turbine 17. The combustion apparatus comprises a fuel pump (not shown) which delivers fuel to a line 18, manifold I9 and nozzles 21. The fuel control may be of anysuitable type, the details of which are immaterial to this invention.

The motive fluid or driving gas discharged from the combustion apparatus 13 flows through the turbine 17 and a power turbine 22 to drive the compressor apparatus I2 and a power output shaft 23. The power output shaft 23 is coupled to the input of the fluid torque transfer device 10. Furthermore, a gear 24 is secured to the output shaft 23 and drives another gear 26 and shaft 27 which may be connected in any suitable manner to a load, such as the input of a transmission (not shown). The gas exhausted from the power turbine is discharged through a duct 28.

The device 10 is shown in FIG. I for simplicity in illustration as directly connected to the output shaft 23 of the engine but it will be recognized that the device 10 may be indirectly connected to said shaft provided only that there is a positive relationship between the device 10 and the shaft 23. It will be recognized further that the parts maybe connected for any desired ratio relationship between the output shaft 23 of the engine and the input of the device 10.

The fluid torque transfer device 10. embodying the invention, in this case a retarding device arranged to limit the speed of the power shaft 23, is illustrated in FIG. 2 and comprises a stationary frame structure 29 having an opening 31 extending therethrough, and a recess 32 surrounding the opening 31 on the right side thereof. A plurality of circumferentially spaced screw openings 30 surround the recess 32. A cup-shaped housing 33 comprises a cylindrical wall 34 and an end wall 36 and an open end 37. A flange 38 projects radially outwardly of the cylindrical wall 34 adjacent the open end and has a plurality of circumferentially spaced openings 39 therethrough which receive screws 41 to secure the housing 33 to the frame member 29. A flange 35 projects axially leftwardly of the flange 38, and is received into the recess 32.

The end wall 36 has a pair of openings 42 and 44 therethrough, said opening 42 being preferably axially aligned with the opening 31 in the frame member 29. A gasket 43 is positioned between the flange 38 and the frame member 29 for purposes of sealing the housing to the frame member 29.

A first bladed member 46 is secured to the stationary end wall 36 by a plurality of screws 47. The first bladed member 46 has a large opening 48 through the center thereof preferably concentric with the opening 42.

A shaft 49 is rotatably supported relative to the frame member 29 by the bearing 51. The bearing 51 is fixed against axial displacement relative to the shaft 49 by a snap ring 52 engaging the left side of the inner race 53 and holding the right "structure 51. Such seal may be further modified as, and if, needed to effect this purpose,

side of the inner race 53 against a shoulder 54. The outer race :56 is prevented from axial movement relative to the frame member 29 by a bearing retaining member 57 which has an by a plurality of screws 61.

t thereof is axially spaced from a shoulder 63 on the shaft 49 to provide a sufficient labyrinth seal to prevent the escape of an excessive amount of fluid from the housing 33into the bearing A second bladed member 66 is positioned within the housing 33 and is securable in any convenient manner to the input shaft 49 such, as here, by being formed integrally therein. The

second bladed member 66 is axially spaced from the first 2O bladed member 46 to define a pressure creating zone 67, an

annular entrance gap 70 into the pressure creating zone and a discharge gap 73 therebetween.

The pressure creating zone 67 is comprised, of the two bladed portions 68 and 69 of the bladed members 46 and 66. 'The bladed portions of the member 46 are positioned in and circumferentially spaced around an annular trough 71 having a semicircular cross section. The bladed portion 68 in this embodiment is inclined with respect to the general plane of the trough 71 and related to the direction of rotation of the member 66 similar to that disclosed in US. Pat. No. 3,291,268 and assigned to the same assignee as the present invention.

The bladed portion 69 of the member 66 is positioned in --and circumferentially spaced around an annular trough 72 having a semicircular cross section. The trough 72 is spaced opposite the trough 71 and the blades 69 are inclined in the same manner as discussed in the aforesaid US. Pat. No. 3,291,268.

The annular gap 70 provides communication between the opening 48 and the pressure creating zone 67. The width of the gap 70 must be great enough to permit entry of the required quantity of fluid necessary to provide the desired degree of coupling between the bladed members 46 and 66. A smooth surface 84 is provided on the second bladed member 66 adjacent the gap 70 to minimize cavitation problems as the fluid is moved into the pressure creating zone 67,

The width dimension of the gap 73 multiplied by the peripheral diameter of the bladed members 46 and 66 defines aperipheral area Al. The cross-sectional area of the opening 44in the end wall 36 is defined as A2. One of the novel features of this invention is that the area A2 is always greater than the area Al so that the fluid pressure at A2 would always be lower than the pressure at the entrance to the gap 73. It is recognized, of course, that in some applications, the area A2 could be made smaller than the area A1 if a pressure creating device such as a pump (not shown) which lowers the fluid pressure on the input side thereof were connected to the opening 44. In which case, the pump would serve to create a low pressure within the housing 33 closely adjacent the outer\ 6O periphery of the bladed members 46 and 66 and the discharge at The fluid circuitry 74 (schematically illustrated in FIG. 2) comprises a conduit 75 which is connected to and extends between the opening 44 and a reservoir 76. A pressure creating device such as a pump 77 delivers fluid from the reservoir 76 through a heat exchanger 78 to a valve 79. A return line 81 is 'provided for delivering fluid from the control valve back to the reservoir 76 when the quantity of fluid delivered by the pump 77 is greater than that required for operation of the torque transfer device. A conduit 82 (schematically illustrated) interconnects the valve 79 with the opening 48 in the bladed member 46. in this particular embodiment. the control valve 79 is controlled by a manually operated mechanism 83. The mechanism 83 may be located in the cab ofa vehicle (not shown) and controlled by the vehicle operator during a transition from one gear range to another gear range to retard the power turbine 22 when the transmission passes through the neutral range during the shift. The control 83 may, of course, also be automatically operated as desired.

OPERATION The operation of the device embodying theinvention will be described in detail hereinbelow for a better understanding of the invention.

The valve 79 serves to control the amount of fluid entering the opening 48 in the bladed member 46. The amount of fluid determines the degree of coupling between the bladed mem' bers 46 and 66. More particularly, where, as here, the width of the gap 73 remains constant, the degree of coupling is directly proportional to the quantity of fluid introduced at the opening 48.

Since, in this particular embodiment, the input shaft 49 is connected to the output shaft 23 of the power turbine of the gas turbine engine 11, the shaft 49 is rotated at a high speed, in the range of 30,000 rpm. Thus, the fluid entering the opening 48 flows smoothly over the surface 84 into the pressure creating zone 67. The driven bladed member 66 effects a centrifugal force on the fluid entering the pressure creating zone 67 and causes same to be thrown radially outwardly. Thus, the fluid is caused to circulate within the toroid formed by the troughs 71 and 72 in the direction of the arrows X. A pressure buildup is developed in the fluid and the centrifugal force effect on the fluid will cause fluid in the pressure creating zone 67 to be forced into and through the discharge gap 73 to flow out therefrom in the direction of the arrows Y.

The quantity of fluid escaping through the discharge gap 73 is of course determined by the difference between the pres sure in the pressure creating zone 67 and the pressure in the housing 33. Because of venting through the labyrinth opening 60, the pressure in the housing 33 will be substantially con stant and will remain substantially at atmospheric level. Further, in this particular embodiment, and preferably, the cross-sectional area A2 of the opening 44 is always larger than the cross-sectional area A1 of the discharge gap 73. Thus, there can be no pressure buildup on the fluid within the housing 33 and the low pressure above mentioned as existing therein remains substantially constant. Therefore, variations in such pressure difference can be brought about with sufficient accuracy solely by varying the pressure within the pressure creating zone 67.

The pressure in the pressure creating zone 67 will, with a constant width of gap 73, depend upon the quantity of fluid circulating in the bladed portions 68 and 69, with the greater quantity of fluid creating a greater pressure. Since for steady state operation the quantity of fluid escaping through the 5 discharge gap 73 equals the quantity of fluid supplied to the opening 48, it follows that if the quantity of fluid per unit time entering the opening 48 is increased, fluid will accumulate in the zone 67 until it develops sufficiently more pressure therein to increase the flow out through the discharge gap 73 to a point at which the flow out through the discharge gap 73 equals the flow in at the opening 48. Similarly, decreasing the quantity of fluid entering the opening 48 will diminish the quantity of fluid within the pressure creating zone 67 and thereby diminish the pressure therein until the flow through the discharge gap 73 diminishes sufficiently so that the inflow and outflow to and from the pressure creating zone 67 is again equalized.

Since the degree of coupling, or torque transmission capacity, at a given spacing of gap 73 is dependent upon the quantity of fluid circulating inthe bladed portions 68 and 69, it will be recognized that the value of coupling force obtained may be increased by increasing the quantity of fluid circulating in the pressure creating zone and may be decreased by decreasing the quantity of such fluid.

Thus, if the operator desires to brake the power turbine 22 to a speed comparable to that of the input shaft of the transmission after a shift from a low-gear range to a high-gear range, the valve 79 can be varied appropriately to vary the flow through the opening 48 manually or automatically, so that the shift can be completed without the operator feeling any jerk as the result of a'sudden engagement of a fast moving member with a slow moving member.

The spacing between the projection 62 and the shoulder 63 permits a small quantity of fluid to escape therethrough to lubricate the bearing 51. However, the primary purpose of the projection 62 is to prevent the escape of an excess quantity of fluid from the housing 33.

MODIFIED CONSTRUCTION OF FIGURES 3 AND 4 A modified fluid torque transfer device A is illustrated in FIGS. 3 and 4. The component parts of the modified torque transfer device 10A will be referred to by the same numerals designating corresponding parts of the torque transfer device 10 but with the suffix A added thereto.

The fluid torque transmitting device 10A is identical to the embodiment illustrated in FIG. 2 except for the bladed member 46A which, in this embodiment, comprises a spiraltype chamber 86 connected in direct communication with the downstream side of the discharge gap 73A. The spiral-type chamber 86 is defined by an extension 87 of the bladed member 46A in a radially outward direction. An outer casing or scroll 88 is secured to the extension 87 by a plurality of screws 89. The extension 87 and the scroll 88 have corresponding recesses therein which when assembled define the spiral-type chamber 86. The scroll 88 is spaced outwardly of the bladed member 66A to define a gap 91-therebetween. The radially inner end of the scroll 88 is spaced radially outwardly of the input shaft 49A to define a gap 92 therebetween.

Referring to FIG. 4, the spiral-type chamber 86 has a maximum diameter as at 93 and a minimum diameter as at 94 ad jacent the discharge opening 96. As in the form of FIG. 2, the discharge opening 96 is of cross-sectional area larger than the peripheral area of the gap 73A. This ensures that the pressure downstream of the gap is lower than that upstream thereof. A projection 97 extends into the chamber-86 to separate the large diameter portion 93 from the small diameter portion 94.

The fluid circuitry 74A (FIG. 3) comprises a conduit 75A which interconnects the opening 44A in the housing 33A with the reservoir 76A. Furthermore, the discharge opening 96 (FIG. 4) is connected to a heat exchanger 99, through a conduit 98 and a check valve 101. A conduit 102 interconnects the heat exchanger 99 and valve 79A. A return line 81A is provided between the valve 79A and the reservoir 76A. In this particular embodiment, a booster pump 103 supplies fluid from the reservoir 76A to the heat exchanger 99 for supplying a quantity of fluid in addition to the quantity of fluid already in the line from the discharge conduit 98 and check valve 101 circuitry.

In operation, the high rotational speedof the input shaft 49A in the direction of the arrow 2 in FIG. 4 effects an appreciably high centrifugal force on the fluid introduced into the pressure creating zone 67A from the opening 48A. The force is sufficient to generate a substantial pressure within the pressure creating zone 67A, said generation of pressure being great enough to create a pumping action forcing the fluid in the pressure creating zone 67A through the discharge gap 73A. The fluid passing through the discharge gap 73A enters the spiral-type chamber 86 of progressively diminishing cross section. The fluid will then pass from the chamber 86 into the discharge opening 96. In this embodiment, the cross-sectional area of the opening 96 is larger than the discharge area of the opening 73A to ensure the creation of a majorpressure within the chamber 67A. Nevertheless, the opening 96 still constricts the flow of fluid through the system sufficiently to create a low-level pressure within the chamber 86 and thereby urge a small amount of the fluid through the conduit 98, check valve 101, heat exchanger 99 and valve 79A for-introduction again into the opening 48A. This type of construction, therefore, eliminates the need for a primary pump such as the pump 77 illustrated in FIG. 2. Instead, only a boost pump 103 is required in order to remove fluid from the reservoir 76A and introduce same into the line 102 at start-up for increasing the coupling engagement between the bladed members 46A and 66A.

Normally, the rotation of the rotor 66A will develop a pressure on any fluid in the gap 91 tending to urge it toward the gap 73A. This provides in effect a seal between the rotor and the scroll 88. However, any leakage which may occur through the gaps 91 and 92 will collect in the housing 33A and then return through the opening 44A, conduit 75A to the reservoir 76A.

The check valve 101 will prevent the pressure developed by the booster pump 103 from causing a fluid backup into the spiral chamber 86.

MODIFIED CONSTRUCTION OF FIGURE 5 The fluid torque transfer device 103 illustrated in FIG. 5 is a device commonly referred to as a fluid coupling wherein both of the bladed members 468 and 66B are supported for rotation with respect to the frame structure 29B as well as relative rotation with respect to each other. The principle embodied in the torque transfer device 10B is the same as that embodied in FIG. 2, the only difference being the manner in which the fluid is introduced into the pressure creating zone 678.

In this particular embodiment, the bladed member 468 is axially spaced from the bladed member 663 to define a discharge gap 738 therebetween.

More particularly, the bladed member 46B is secured in any convenient manner to an output shaft 106. The output shaft 106 is rotatably supported relative to the housing 338 by a pair of axially spaced bearings 107 and 108.

In this particular embodiment, the shaft 106 is prevented from leftward axial movement by the snap ring 112 acting against the bearing 107 which is in turn prevented from leftward movement by the bearing retainer 109 which is secured by screws 111 to housing 338. Said shaft is prevented from rightward movement by the shoulder of said shaft acting against the bearing 107 and urging same against the shoulder 115 in the housing 33B. The bearing 108 is held in position between the shoulder 114 on said shaft and the snap ring 113.

A radial passageway 116 is provided through the shaft 106 in an area between the axially spaced bearings I07 and 108. A passageway 117 interconnects the passageway 116 with the pressure creating zone 678 between the bladed members 46B and 668.

An opening 118 is provided in the housing 338. A fluid supplying device 119 encircles the shaft 106 between the bearings 107 and 108 and is axially positioned by a pair of snap rings 121 and 122. The fluid supplying device 119 is properly sealed against the shaft 106 on both sides of the passageway 116 and on both sides of the opening 118 so that leakage therefrom will be minimized. The fluid supplying device 119 has an opening 123 therethrough so that fluid introduced into the opening 118 will pass through the opening 123 into passageways 116 and 117 to the pressure creating zone 67B.

In operation, the degree of coupling between the bladed members 468 and 66B is directly proportional to the quantity of fluid introduced into the pressure creating zone 678. Thus, the torque on the output shaft 106 of the torque transfer device 103 can be regulated by varying the quantity of fluid introduced into the pressure creating zone 678.

The fluid which escapes through the discharge gap 73B will enter the housing 333 and exit through opening 443 and may, if desired, be returned to the inlet 118 through a return system 748 similar to the return system 74. As was. discussed above with respect to FIG. 2, the cross-sectional area of the opening 443 is always greater than the peripheral area defined by the discharge gap 738. Therefore, a buildup of pressure on the MODIFIED CONSTRUCTION OF FIGURE 6 The modified fluid torque transfer device 10C illustrated in FIG. 6 is identical to the torque transfer device 105 illustrated in FIG. with the exception that the bladed member 46C is movable axially relative to the bladed member 66C. This par- .ticular adjustment feature comprises an annular member 124 "which is threadedly engaged with the housing 33C. A handle .126 is secured to the annular member 124 so that same can be jI'flOVeCl to increase or decrease the threaded engagement of the annular member with the housing 33C. In this particular embodiment, the bearings 107C and 108C are securely fastened to the shaft 106C so as to prevent an axial movement relative thereto. However, the outer race of each of the bearings 107C and 108C are permitted to slide axially within the housing 33C.

The inner end of the annular member 124 engages the outer race of the bearing 108C. Thus, by an appropriate manipulation of the handle 126, the threaded engagement of the annular member 124 may be increased so that the bearing 108C is urged leftwardly. Since the bearing 108C is securely fastened against movement relative to the shaft 106C, the shaft 106C and the bearing 107C will be moved leftwardly also. Leftward movement of the shaft 106C will diminish the size of the discharge gap 73C between the bladed members 46C and 66C.

Thus, assuming a constant quantity of fluid input into the opening 118C and the pressure creating zone 67C, by diminishing the size of the discharge gap 73C the amount of pressure in the pressure creating zone 67C will be increased.

As stated above, an increase in pressure in the pressure creating zone 67C is obtained by an increase in the quantity of fluid in the pressure creating zone and will accordingly increase the fluid coupling engagement of the input shaft 49C with the output shaft 106C.

'Although the shaft 106C is permitted to move axially within the housing BBC, the fluid supplying member 119C will remain fixed to the housing 33C by the snap rings 121C and 122C and will always permit a fluid'connection of the opening 118C with the opening 123C, radial passageway 116C, passageway 117C and the pressure creating zone 67C.

Similarly, movement of the annular member 124 to the right permits the pressure within chamber 67C to move the bladed member 46C, and parts associated therewith, to the right whereby to increase the width of the discharge gap 73C. This lowers the magnitude of pressure within the pressure creating zone 67C required to effect the escape through the gap 73C of a'given quantity of circulating fluid. Thus, the quantity of fluid in the pressure creating zone 67C diminishes until the proper pressure is reached to maintain a selected quantity of flow through the system and such decrease in the quantity of fluid decreases the torque transmission capacity between the input shaft 49C and the output shaft 106C.

Alternatively, if desired, an increase in the size of the gap 73C may be utilized with an increased volume of liquid being into introduced at opening 117C to maintain a given magnitude of torque transfer with, for example, an increased capacity to carry off heat.

However, the maximum width of the discharge gap 73C will always be at a dimension which will define an area (corresponding to the area A1 in FIG. 2) which is always less than the area (corresponding to the area A2 in FIG. 2) of the opening 44C in the housing 33C. Thus, at no time will a pressure buildup occur in the fluid in the housing 33C and a low pres sure will always exist at the downstream of side of the discharge gap 73C.

As before, the fluid from the exit 44C may, if desired, be returned to the inlet by a return system 74C, which may be similar to the return system 74 excepting that here, if desired, the regulating valve 79C may, but need not necessarily, be

omitted in view of the regulation provided by adjusting the width of the discharge gap 73C.

I claim:

1. A fluid torque transfer device having frame means and at least one shaft supported for relative rotation with respect to said frame means, comprising in combination:

first and second spaced, coaxial, bladed members, said axial spacing defining a pressure creating zone and a discharge gap therebetween;

an inlet for introducing working fluid into said pressure creating zone;

fluid circuitry means for supplying a variable volume of pressurized fluid to said inlet, said pressure creating zone and said discharge gap; and

fluid accumulation means adjacent the downstream side of said discharge gap for receiving the fluid discharged from said discharge gap, means in said fluid accumulation means for maintaining a constant low pressure on the fluid in said fluid accumulation means immediately adjacent said discharge gap and independent of the volume of pressurized fluid entering said inlet so that a major pressure drop in said fluid circuitry means will occur across said discharge gap, and means for providing a return of said fluid from said accumulation means to said fluid circuitry means without changing, at least appreciably, the pressure on said fluid adjacent said gap to thereby permit an accurate control of said fluid torque transfer device by regulating the volume of fluid to said inlet.

2. A fluid torque transfer device as defined in claim 1, wherein said second bladed member is fixed to said frame means.

3. A fluid torque transfer device as defined in claim 1,

wherein said discharge gap defines a first cross-sectional area; and

wherein said means for providing a return of said fluid in said fluid accumulation means to said fluid circuitry means includes a return opening in said fluid accumulation means having a second cross-sectional area which is greater than said first area to thereby prevent a buildup of pressure on said fluid in said fluid accumulation means and to assure that the major pressure drop in said fluid circuitry means will occur across said discharge gap.

4. A fluid torque transfer device as defined in claim 3, wherein said fluid accumulation means comprises an outer casing which surrounds said first and second bladed members.

5. A fluid torque transfer device as defined in claim 1, including means for adjusting said axial spacing whereby said discharge gap is variable to 'regulate'the quantity of fluid escaping therefrom to thereby regulate the degree ofcoupling between said first and second bladed members.

6. A fluid torque transfer device a as defined in claim 1, wherein said means for maintaining a constant low pressure on the fluid in said fluid accumulation means includes a passageway communicating with the atmosphere to maintain the fluid in said fluid accumulation means at atmospheric pressure.

7. A fluid torque transfer device having frame means and at least one shaft supported for relative rotation with respect to said frame means, comprising in combination:

a pair of spaced, coaxial, bladed rotors, said axial spacing defining a pressure creating zone and a discharge gap therebetween, said discharge gap having a first cross-sectional area;

fluid circuitry means supplying fluid to said pressure creating zone and said discharge gap;

fluid accumulation means comprising an outer casing a surrounding said pair of bladed rotors, said outer casing having spiral-shaped chamber means therein in fluid communication with said discharge gap so that fluid discharged through said gap will collect in said fluid accumulation means; and

means defining a return opening in said fluid accumulation means having a second cross-sectional area which is greater than said first area to assure that the fluid pressure in said fluid accumulation means is less than the fluid pressure in said pressure creating zone so that a major pressure drop will occur across said discharge gap, said spiral-shaped chamber means having a discharge opening connected in circuit with said discharge gap, said fluid circuitry means connected in circuit with said discharge opening and said pressure creating zone whereby the pressure created in said pressure creating zone and said spiral-shaped chamber means will drive the fluid through said fluid circuitry.

8. In a fluid torque transfer device, thecombination comprising:

a housing;

a pair of spaced, coaxial, bladed rotors mounted within said housing with one of said rotors being mounted for rotation relative to the other, each thereof having an annular groove therein substantially opposing and cooperating with the corresponding annular groovevof the other to define an annular pressure creating zone, and blades being arranged within said annular grooves for providing a plurality of successive vortexes within said zone;

inlet means for introducing working fluid through the center of one of said rotors into at least one of said annular grooves throughout substantially the full circumference thereof and said rotors being sufficiently spaced from each other to provide an exit gap for said fluid between said rotors at the outer diameter of said grooves throughout at least substantially the full circumference thereof; and

fluid accumulation means adjacent the downstream side of said discharge gap for receiving the fluid discharged from said discharge gap, means in said fluid accumulation means for maintaining a constant low pressure on the fluid in said fluid accumulation means immediately adjacent said discharged gap and independent of the volume of pressurized fluid entering said inlet means so that a major pressure drop in said fluid circuitry means will occur across said discharge gap, and means for providing a return of said fluid in said fluid accumulation means to said fluid circuitry means without changing, at least appreeiably, the pressure on said fluid adjacent said gap to thereby permit an accurate control of said fluid torque transfer device by regulating the volume of fluid admitted into said inlet means.

9. The device defined in claim 8. wherein said means for providing a return of said fluid in said fluid accumulation means to said inlet means includes a discharge opening in said housing, said discharge opening being larger in area than the area of said exit gap to prevent a buildup of pressure on said fluid in said fluid accumulation means.

10. The device defined in claim 8, wherein means are provided for receiving fluid at a low pressure from said discharge opening and returning it to said inlet opening at a higher pressure.

11. The device defined in claim 8, including also valve means to regulate the amount of fluid supplied to said annular pressure creating zone to regulate the degree of coupling between said pair of bladed rotors.

12. The device defined in claim 8, wherein said fluid accumulation means surrounds said exit gap and is in direct communication therewith whereby fluid from said discharge gap enters directly into the fluid accumulation means.

13. The device defined in claim 8, wherein said fluid accumulation means is fixed against rotation. I

14. ln a fluid torque transfer device, the combination comprising:

a pair of spaced, coaxial, bladed rotors mounted for relative rotation with respect to each other, the blades thereof being juxtaposed axially with respect to each other and constituting a pressure creating zone and the spacing between said rotors constituting a discharge orifice from said zone; inlet means introducing pressure fluid mto said zone;

centric of said rotors.

16. The device of claim 14, wherein said inlet means is annular and concentric of said rotors.

17. The device defined in claim 14, wherein said fluid circuitry includes means regulating the quantity of fluid entering said pressure creating zone. 

